When we open a cold water tap the first water is cool and then it gets almost hot before we receive any cold water - what would cause this situation?

Sounds like you have either a hot water pipe next to a cold water pipe, and it takes a few seconds to cool it down... or the pipe runs across the roofline or against a south wall that the water has gotten heated up in...

Just to elaborate a bit on what Chris was saying: the pipe between the water main and the sink are always full of water. If that pipe passes through a very hot area (such as right near a furnace), the water sitting in the pipe at that location can get very hot. Then, when you turn on the sink and the water starts moving, that burst of hot water needs to be "flushed out" before the new, colder, water can come through. As long as the water is moving, it will stay cold. When you shut the water, however, it comes to a stop, and whichever part of the water is near the heat source begins to heat up again, and the process repeats itself...

Hope this helps,
Moishe
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